STM8L External interrupt PortB and PortD with rising/falling configuration

[davide239955_st]

Hello everybody,

In my project which uses STM8L151G6 MCU, I need 6 interrupt inputs on both rising/falling edge. In particular those pins are PB0, PB1, PB2, PD1, PD2, PD3.

Please note I'm using "port interrupt mode", i.e. EXTIB_G_IRQHandler and EXTID_H_IRQHandler are used.

If all pins of the port (for example PB) are "floating" (internally pulled-up), then the first one which falls, it triggers EXTIB_G_IRQHandler interrupt as expected and everything it works.

But, if 1 pin among PB0, PB1 and PB2 is already low, then interrupt is not triggered by the other pins even if EXTI->SR2 register has been "cleared" inside the interrupt handler.

I have reduced the project to a very simple test code in order to reproduce the issue. Please find attached the project folder so you may test.

TEST procedure:

-set breakpoints in EXTIB_G_IRQHandler, EXTID_H_IRQHandler and EXTI0_IRQHandler...EXTI7_IRQHandler

-start debug

-leave PB0,PB1,PB2 "open" and connect one of them to GND -> interrupt EXTIB_G_IRQHandler is triggered

-open the pin and test another one -> interrupt is triggered

Now...

-connect one pin to GND (e.g. PB0) and leave it connected to GND

-test another pin (e.g. PB1) -> interrupt is not triggered anymore until PB0 is released

-same procedure apply to PD1,PD2,PD3 group of pins.

What am I wrong? Is the EXTI invalid configuration?

Thanks

[Cristian Gyorgy]

Hi!

What you experience is normal. If you use only one interrupt (EXTIB_G) for the 3 PB pins, all 3 pins are and-wired to the interrupt controller input, so if one of the 3 pins is low, a change of state for the other pins will not trigger an interrupt, see manual RM0031.

If you need 6 external interrupts, you should use the EXTI0..7 with a different pins usage, or a combinations of interrupts.

[AA1]

Hi,

I have already detected this problem. Tell me the RM0031 page where says that all pins are and-wired?

And STM8S family don't have this behavior.

RM0031 external interrupt section needs to be improved.

[davide239955_st]

Thanks for reply. I found the "and-wired" schematic in GPIO section of RM0031 (page 118)

https://www.st.com/resource/en/reference_manual/rm0031-stm8l050j3-stm8l051f3-stm8l052c6-stm8l052r8-mcus-and-stm8l151l152-stm8l162-stm8al31-stm8al3l-lines-stmicroelectronics.pdf

[AA1]

It is in GPIO section. And STM8S RM0016 page106 have same schematic and have different behavior. On STM8S interrupts on same port works independently.

As I said RM0031 external interrupt section needs to be improved. Also manual needs a revision. For example external interrupt section have bad formatted text.